Learning objectives

Describe how Tycho Brahe and Johannes Kepler contributed to our understanding of how planets move around the Sun

Explain Kepler’s three laws of planetary motion

At about the time that
Galileo was beginning his experiments with falling bodies, the efforts of two other scientists dramatically advanced our understanding of the motions of the planets. These two astronomers were the observer Tycho Brahe and the mathematician Johannes Kepler. Together, they placed the speculations of Copernicus on a sound mathematical basis and paved the way for the work of Isaac Newton in the next century.

Tycho brahe’s observatory

Three years after the publication of Copernicus’
De Revolutionibus , Tycho
Brahe was born to a family of Danish nobility. He developed an early interest in astronomy and, as a young man, made significant astronomical observations. Among these was a careful study of what we now know was an exploding star that flared up to great brilliance in the night sky. His growing reputation gained him the patronage of the Danish King Frederick II, and at the age of 30, Brahe was able to establish a fine astronomical observatory on the North Sea island of Hven (
[link] ). Brahe was the last and greatest of the pre-telescopic observers in Europe.

Tycho brahe (1546–1601) and johannes kepler (1571–1630).

(a) A stylized engraving shows Tycho Brahe using his instruments to measure the altitude of celestial objects above the horizon. The large curved instrument in the foreground allowed him to measure precise angles in the sky. Note that the scene includes hints of the grandeur of Brahe’s observatory at Hven. (b) Kepler was a German mathematician and astronomer. His discovery of the basic laws that describe planetary motion placed the heliocentric cosmology of Copernicus on a firm mathematical basis.

At Hven, Brahe made a continuous record of the positions of the Sun, Moon, and planets for almost 20 years. His extensive and precise observations enabled him to note that the positions of the planets varied from those given in published tables, which were based on the work of Ptolemy. These data were extremely valuable, but Brahe didn’t have the ability to analyze them and develop a better model than what Ptolemy had published. He was further inhibited because he was an extravagant and cantankerous fellow, and he accumulated enemies among government officials. When his patron, Frederick II, died in 1597, Brahe lost his political base and decided to leave Denmark. He took up residence in Prague, where he became court astronomer to Emperor Rudolf of Bohemia. There, in the year before his death, Brahe found a most able young mathematician, Johannes Kepler, to assist him in analyzing his extensive planetary data.

Johannes kepler

Johannes
Kepler was born into a poor family in the German province of Württemberg and lived much of his life amid the turmoil of the Thirty Years’ War (see
[link] ). He attended university at Tubingen and studied for a theological career. There, he learned the principles of the Copernican system and became converted to the heliocentric hypothesis. Eventually, Kepler went to Prague to serve as an assistant to Brahe, who set him to work trying to find a satisfactory theory of planetary motion—one that was compatible with the long series of observations made at Hven. Brahe was reluctant to provide Kepler with much material at any one time for fear that Kepler would discover the secrets of the universal motion by himself, thereby robbing Brahe of some of the glory. Only after Brahe’s death in 1601 did Kepler get full possession of the priceless records. Their study occupied most of Kepler’s time for more than 20 years.

The largest observatory complex in the world is on Mauna Kea, the tallest mountain on Earth. Whatare some factors astronomers consider when selecting an observatory site? Don’t forget practical ones.Should astronomers, for example, consider building an observatory on Denali (Mount McKinley) or MountEverest?

We are part of the Milky Way Galaxy. We are within it, so it's not really away from us. Our galaxy is 100,000 light years in diameter. The nearest big galaxy is Andromeda, around 2 million lightyears away.

im in 8th standard and my school teach us nothing about astronomy but i want to be an astronomer so i study from youtube and apps like this but sometimes i get language problems

Rishabh

dark**

Glory

side**

Glory

The Moon does actually rotate. It takes 27 days for the Moon to make a full rotation. Because it takes it so long and the Earth is rotating around the sun, it seems like the Moon is pretty much standing still. That's called "synchronous rotation".

steveh259

I ment to say "The Earth is orbiting around the sun"

steveh259

Tidal Locked.....

Adam

***svs.gsfc.nasa.gov/4442

Collins

thats cool

Gospel

ya gives you a look at how the moon orbits around us too and a perspective of how fast we are going. also gives the moon phases for the year! enjoy 😁

Collins

yes you are absolutely correct, it just like something like the milk of heaven

the moon has a 28 day cycle. you can download a moon calander or follow the pattern and make your own calendar. 1st full moon of the year 21/22nd Jan, its also a blood moon and a wolf moon. if this info helps at all. 😊

What it means by Big Bang is how the world was made and came in to exist

Glory

The Big Bang Is The Best Explanation For What We See Around Us, And For The Origin Of The Universe, All Our Evidence Points To The Big Bang Theory..... And Was Proposed By A Belgian Priest.....

Adam

if the big bang theory is really true than i would like to know what exploded and where did it came from and where did the energy came from and where come from for the matter to expand into amd where did the organization come from and where did the information come from.........

Gospel

Some say that on the otherside of the singularity was a black hole. They say that at the other end of all black holes is another universe. Hence the multiverse. It's all theoretical at this point but less than a 100 years ago people believed that there was only 1 galaxy in the universe. So why

Rafael

should there be only 1 universe?

Rafael

universe.

Rafael

Big Bang is a theory on the origin of the universe.It says that the whole universe started as an infinitely dense and hot point,which expanded with time to form the universe in which we live today.

priyanshu

but if you study about string theory then you will come to know that before big bang there were string ( vibrating particles) which cause to form the conditions for big bang.

YOG

Hmm,actually,I dont know much about string theory,just a little.I just wanted to tell this guy what is the Big Bang Theory.

priyanshu

and according to string theory black holes are giant fuzzball of strings,there is no infinity dense singularity and no smooth horizon there is just only a ball of string

YOG

Join the discussion...

is astronomy a hard subject to learn because i want to be an astronomer

if your already interested/observing, your already an astronomer ! The more you look and read the more you'll learn.

Collins

I want to become a scientist but my knowledge is very low. How I can improve my knowledge?

Wwe

any form of science courses, there's free crash course channel on you tube. I've learned alot from this channel. covers most topics, science: biology chemistry physics, astronomy, ranges to anatomy, history and many many more. it's a never ending subject!

Collins

suggest a channel as a example

Wwe

CrashCourse is the name of the channel and there is a picture of an apple. look through their play lists. They will have other related channels they follow also.

Collins

thank you so much

Wwe

your very welcome

Collins

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Why are they so far away that their light takes hundreds of millions of years to reach us on earth?